The bacterial protein H-NS acts to silence horizontally acquired genes. H-NS physically interacts via its N-terminus with two paralogous proteins, Hha and YdgT. Deletion of hha and ydgT results in derepression of a subset of H-NS repressed genes. I compared expression of hha/ydgT-dependent genes in Salmonella strains lacking hns and hha/ydgT/hns. Deletion of all three genes does not result in greater gene expression than deletion of hns alone, indicating that Hha and YdgT cannot act to repress genes in the absence of H-NS. Further, I used site-directed mutagenesis to generate H-NS proteins incapable of binding Hha. Complementing an hns deletion with an Hha-blind H-NS molecule, H-NS I11A, recapitulated the pattern of gene expression in the hha/ydgT strain. Indicating that elimination of the Hha-H-NS interaction is sufficient to result in derepression of hha/ydgT repressed genes. Hha and YdgT repress gene expression by acting through H-NS and cannot act independently of H-NS.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/25812 |
| Date | 11 January 2011 |
| Creators | Stevenson, James |
| Contributors | Navarre, William |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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